Magnets

[Luckless]

My GPS seems to be working a little crazy sometimes.

I was wondering if magnets in my backpack with the GPS could have had an affect on it.

[ossumguywill]

Magnets can corrupt digital data.

[peter]

Magnets can corrupt digital data.

Magnets can corrupt data, whether analog or digital, on certain types of media. But I doubt Luckless' GPS has either magnetic tape or a magnetic disk as the storage device.

 

OTOH, he might have a magnetic compass sensor and that could be affected by nearby magnets. It would be good to know what model of GPS he has and just what is meant by "a little crazy." The basic GPS functions wouldn't be affected by nearby magnets unless they're positioned right over the antenna and block reception.

[malcolmspeak]

Hi

I dont know what model you have, but magnets generally will corrupt digital data if they are strong enough.

Having said that, most new units are reasonably robust in this respect, for example, I keep my Holux GPSlim236 in the same pocket that I keep its antenna (which has a magnetic base) and have never had a problem.

 

If you have a built in magnetic compass sensor, it may be affected by haematite (iron ore) or magnetite in the ground if you go off road a lot.

 

My suggestion would be to get a normal magnetic compass and move it around the objects you usually carry, and hold it in the relative position you keep your GPS. Any sudden deviation in the needle will point out possible culprits. Remove those from the scene and try again. Try this also with a location that you know affects your GPS. This may prove the above point.

 

The other possiblity (remember, I dont know what GPS you have) is that you've used a SIRFIII gps and left it in SIRF mode when changing to a piece of software that uses only NMEA input.

 

Remember too, unless you have a magnetic compass built into the GPS that GPS receivers aren't much good as compasses unless you are moving, then they work on the differences betyween signals before giving the direction.

 

I hope some of this helps, GPS units can be curious things.

 

peace

 

Malcolm

[Alphawolf]

Curious minds want to know...

Why do you have magnets in your backpack? I've done a lot of backpacking, but that is something that has never found its way into my pack.

[GermanSailor]

Hello,

 

I doubt that a magnet can corrupt digital data.

 

Print this out and hold a magnet to it:

 

1010100110011001101010101

 

Guess nothing happened.

 

Magnets can destroy digital (and analog) data which is stored on a magnetic media.

 

I tried if a really powerful Neodymium magnet can destroy a SD card, but nothing happened. Floppy Disks, Audio Tapes, Hard Drives are another storty.

 

Again: It is the media which matters. I seriously doubt that the GPS signal is affected by a magnetic field next to the receiver. (Not talking about space and ionosphere here.)

 

GermanSailor

[+Crystal Sound]

I've used my GPS in a 765,000 volt substations (under the busswork) and never had a data corruption...

 

I have felt my bones vibrate from the magnetic resonance, however...

 

Our field techs have carried USB memory devices (in the same environment), and not had any trouble. Floppy discs have come up "erased" quite often.

[Neo_Geo]

Hello,

I doubt that a magnet can corrupt digital data.

Print this out and hold a magnet to it:

1010100110011001101010101

Guess nothing happened.

Magnets can destroy digital (and analog) data which is stored on a magnetic media.

I tried if a really powerful Neodymium magnet can destroy a SD card, but nothing happened. Floppy Disks, Audio Tapes, Hard Drives are another storty.

Again: It is the media which matters. I seriously doubt that the GPS signal is affected by a magnetic field next to the receiver. (Not talking about space and ionosphere here.)

GermanSailor

Once you print it out, it's no longer "digital" - it becomes printed material which I consider analogous. Now, if you download this thread with a wireless connection, and you put a magnet up to the antenna, then your ones and zeroes would be in digital format and would very well be subject to corruption!

[Luckless]

I have a Megellan Sports Pro (with the warranty about ready to expire and when things always start acting funny.)

The magnet was on a keyholder to be used as a cache. (They make those fairly strong so they don't fall off the car while in motion.)

I just was wondering if that was something I needed to be concerned about.

[peter]

I have a Megellan Sports Pro (with the warranty about ready to expire and when things always start acting funny.)

The magnet was on a keyholder to be used as a cache. (They make those fairly strong so they don't fall off the car while in motion.)

I just was wondering if that was something I needed to be concerned about.

If it's acting funny it may be something to be concerned about, but, no, it wouldn't have anything to do with the nearby magnet.

 

This thread has sure brought out some interesting comments about perceptions of digital vs. analog data - like the idea that printed digits are somehow not digital.

[ossumguywill]

A magnet can also interrupt signals going through a microproccessor. A current generates it's own magnetic field. If you hold a magnet to a 9 volt current, nothing will happen. But since the current of each little microscopic silicon wire in the microproccessor of your gpsr is like 1/1000,000,000th of a volt (just guessing, I don't know exactly), the magnet can interrupt the signal. Also, since an SD card works by storing charges in metal capacitors, can't you mess those up with a magnetic field strong enough to shift them?

Edited October 27, 2006 by ossumguywill

[peter]

A magnet can also interrupt signals going through a microproccessor. A current generates it's own magnetic field. If you hold a magnet to a 9 volt current, nothing will happen. But since the current of each little microscopic silicon wire in the microproccessor of your gpsr is like 1/1000,000,000th of a volt (just guessing, I don't know exactly), the magnet can interrupt the signal. Also, since an SD card works by storing charges in metal capacitors, can't you mess those up with a magnetic field strong enough to shift them?

No, both your microprocessor chips and flash memory devices are perfectly safe in proximity to a magnet. And although the current through any particular gate in a microprocessor or similar electronic device will be very small, the voltage is still at a decent level (typ. a few tenths to a few volts).

[GermanSailor]

Also, since an SD card works by storing charges in metal capacitors, can't you mess those up with a magnetic field strong enough to shift them?

No, apparently you can't.

 

I got a completely useless 32 MB SD Card with my new 7 MegaPix Camera. (It can store 9 Pictures on it, thank you Canon). So I tried killing it with a neodymium magnet - nothing happened to the data.

 

Neo_Geo: No offence, but I think you up the terms data und media here.

 

0101101001 is digital no matter on what type of media you store it.

 

Some media uses magnetic field to store data, like the good old audio tape. If you expose such a tape to a magnet the data stored on it will be affected. No matter if it is analog (music) or digital.

 

If it write down my digital info (0110...) on a pice of paper it's still digital, but I now stored it optical not magnetic, so it is not affected by a magnetic field.

 

A CD for example isn't affected by a magnet, since the data is stored optical, even it is still digital data.

 

GermanSailor

Edited October 27, 2006 by GermanSailor

[ossumguywill]

Also, since an SD card works by storing charges in metal capacitors, can't you mess those up with a magnetic field strong enough to shift them?

No, apparently you can't.

 

I got a completely useless 32 MB SD Card with my new 7 MegaPix Camera. (It can store 9 Pictures on it, thank you Canon). So I tried killing it with a neodymium magnet - nothing happened to the data.

 

Neo_Geo: No offence, but I think you up the terms data und media here.

 

0101101001 is digital no matter on what type of media you store it.

 

Some media uses magnetic field to store data, like the good old audio tape. If you expose such a tape to a magnet the data stored on it will be affected. No matter if it is analog (music) or digital.

 

If it write down my digital info (0110...) on a pice of paper it's still digital, but I now stored it optical not magnetic, so it is not affected by a magnetic field.

 

A CD for example isn't affected by a magnet, since the data is stored optical, even it is still digital data.

 

GermanSailor

Actaully, the bumps on CDs that refract light are made by a neodyum magnet. I think you will find that you can kill a CD.

[GermanSailor]

Actaully, the bumps on CDs that refract light are made by a neodyum magnet. I think you will find that you can kill a CD.

Hi,

 

there is just one way to find this one out. Now I know what David Hasselhoff CD's are good for!

 

(I hope you are right!)

 

GermanSailor

 

Update:

 

No, you can`t kill it. Had to throw it away the old fashioned way. ;-)

 

Checked Wikipedia on the subject. It doesn't mention a magnet.

Edited October 28, 2006 by GermanSailor

[ossumguywill]

Actaully, the bumps on CDs that refract light are made by a neodyum magnet. I think you will find that you can kill a CD.

Hi,

 

there is just one way to find this one out. Now I know what David Hasselhoff CD's are good for!

 

(I hope you are right!)

 

GermanSailor

 

Update:

 

No, you can`t kill it. Had to throw it away the old fashioned way. ;-)

 

Checked Wikipedia on the subject. It doesn't mention a magnet.

Writable CDs (I am pretty sure david hasslehoff's cds are unwritable) are killable. This has to be true because your computer uses magnets to write a CD and a laser to read them.

[GermanSailor]

Hi,

 

we are really off-topic now.

 

Since I didn't want to kill one of my burnt CDs, I just checked Wiki again. No magnetical system either.

 

I guess we are talking about two different things here. You probably mean Magneto-optical discs, since the "normal" ones are definitely recorded magnetically. The laser melts the information on them.

 

GermanSailor

[ossumguywill]

Wow. How many mw.s would a laser have to be to burn a reflective piece of metal?!

[+GOT GPS?]

The SporTrak Pro may have been messed up by any number of things, including moisture, dirt, metal particles inside, Gamma Ray Bursts, corupted data, etc.

 

When the GPS is subjected to enough shock, it could render the unit no longer waterproof, and also metal particles could develope, causing the circuitry to act flaky, and even microscopic particles loose inside the silicon chips in the GPS. Loose particles could develope from the tiny wires that connect the pins of the chips to the chips themselves, and these loose particles could be effected by magnets.

 

High frequency radiation could momentarily damage the GPS, like Gamma Rays or other sources.

 

----------------

 

Things to do:

 

Go and RESET ALL in the SporTrak Pro, then download the last available firmware from Magellangps.com, then RESET ALL again, then place the GPS out in the open for at least 20 minutes to get a good clean satellite almanac, and this is best done in an open area away from tall objects.

 

- - - - -

 

If the unit still is acting up, then something in the circuitry is flaking out.

 

Edited: Particles, not particals

Edited October 28, 2006 by GOT GPS?

[+SimonC_Here]

Wow. How many mw.s would a laser have to be to burn a reflective piece of metal?!

 

Probably quite a lot but as CD-RW and CD-R work by heating up a layer of dye inside the disk to make it turn opaque which is then interpreted by the reading laser as a "bump" it doesn't have to be that hot.

 

Howstuffworks

 

Simon

[malcolmspeak]

Hi

Im curious about this (hence my second reply). What do you use the magnets in your backpack for? If you are carrying the gps in your hand, or on a lanyard or belt, it should be far enough away for even really powerful magnets to be ineffective.

 

Exactly what effect does the problem manfest as. Positioning data shouldn't be affected.

 

One idea... moving a conductor (i.e. antenna) through a magneticfield will generate an electric current. That's how generators work. An idea I had was to use an external antenna, but put a ferrite ring around the cable (and loop the cable through it to hold it still). Try your readings then.

 

If you have Garmin, put the ferrite ring around the antenna that pokes up and never quite allows me to close the zip on the bag.

 

When I worked in the electronics industry, we used to put ferrite around most communications cables to prevent spikes and interference. Rings come in various sizes and in blocks too. Maybe you could put a bloch above your antenna if its an inbuilt ceramic patch type (not sure if this one will work, you may block the signal completely).

Ferrite items can be found at your local electronics store or wholesaler cheaply.

 

peace

 

Malcolm

 

Malcolm

[John E Cache]

My GPS seems to be working a little crazy sometimes.

I was wondering if magnets in my backpack with the GPS could have had an affect on it.

It sounds like you carry your GPS in your pack with magnets and you want to know if the magnets will magnitize the GPS when off. I don't think so. There shouldn't be any thing magnetic in the GPS because of the compass.